He attributed Valve's success to the PC's open nature, saying that the company "wouldn't exist" without either the PC or "the openness of the platform." That openness is under threat, though. Newell argues that there is a "strong temptation" to close the platform, because the platform's developers "look at what they can accomplish when they limit the competitors’ access to the platform, and they say 'That's really exciting.'"

Compare, for instance, OS X Mountain Lion to Windows 8. OS X, while borrowing some features from its tablet/mobile counterpart, iOS, is still distinctly a PC operating system. It has a traditional window manager as its primary UI, root access to the file system, and it can run unsigned code without being jailbroken.

Windows 8, on the other hand, demotes the “legacy” desktop in favour of finger-friendly Metro. It’s an uncomfortable hodgepodge between locked-down tablet OS and clunking desktop leviathan. Windows RT, in particular, seems to consist of the worst of both worlds: an Explorer shell rattling around solely for the purpose of running Microsoft Office, and the fact that Windows ARM tablets will be, to all intents and purposes, unable to run unsigned code.

I suspect that, within a year or two, many Windows power users will seriously be contemplating a switch to OS X or Linux. Within five years, Linux will be the most popular platform for hardcore PC gaming, with OS X favoured by those who enjoy occasional rounds of TF2.